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"Xiang, Zheng"
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Analytics in smart tourism design : concepts and methods
Presenting cutting edge research on the development of analytics in travel and tourism, this text introduces new conceptual frameworks and measurement tools, as well as applications and case studies for destination marketing and management.
Book
Strongly lensed repeating fast radio bursts as precision probes of the universe
Fast radio bursts (FRBs), bright transients with millisecond durations at ∼GHz and typical redshifts probably >0.8, are likely to be gravitationally lensed by intervening galaxies. Since the time delay between images of strongly lensed FRB can be measured to extremely high precision because of the large ratio ∼10
9
between the typical galaxy-lensing delay time
~
O
(10 days) and the width of bursts
~
O
(ms), we propose strongly lensed FRBs as precision probes of the universe. We show that, within the flat ΛCDM model, the Hubble constant
H
0
can be constrained with a ~0.91% uncertainty from 10 such systems probably observed with the square kilometer array (SKA) in <30 years. More importantly, the cosmic curvature can be model independently constrained to a precision of ∼0.076. This constraint can directly test the validity of the cosmological principle and break the intractable degeneracy between the cosmic curvature and dark energy.
Fast radio bursts (FRBs) are likely to be gravitationally lensed by intervening galaxies. Here, the authors propose to make accurate measurements of time delays between images of lensed FRBs as a powerful probe for precision cosmology.
Journal Article
Design science in tourism : foundations of destination management
\"This book explores the impact of design science and design thinking on tourism planning, gathering contributions from leading authorities in the field of tourism research and providing a comprehensive and interconnected panorama of cutting-edge results that influence the current and future design of tourist destinations.\"--Back cover.
BOOK
A model for the evolution of the Earth's mantle structure since the Early Paleozoic
Seismic tomography studies indicate that the Earth's mantle structure is characterized by African and Pacific seismically slow velocity anomalies (i.e., superplumes) and circum‐Pacific seismically fast anomalies (i.e., a globally spherical harmonic degree 2 structure). However, the cause for and time evolution of the African and Pacific superplumes and the degree 2 mantle structure remain poorly understood with two competing proposals. First, the African and Pacific superplumes have remained largely unchanged for at least the last 300 Myr and possibly much longer. Second, the African superplume is formed sometime after the formation of Pangea (i.e., at 330 Ma) and the mantle in the African hemisphere is predominated by cold downwelling structures before and during the assembly of Pangea, while the Pacific superplume has been stable for the Pangea supercontinent cycle (i.e., globally a degree 1 structure before the Pangea formation). Here, we construct a proxy model of plate motions for the African hemisphere for the last 450 Myr since the Early Paleozoic using the paleogeographic reconstruction of continents constrained by paleomagnetic and geological observations. Coupled with assumed oceanic plate motions for the Pacific hemisphere, this proxy model for the plate motion history is used as time‐dependent surface boundary condition in three‐dimensional spherical models of thermochemical mantle convection to study the evolution of mantle structure, particularly the African mantle structure, since the Early Paleozoic. Our model calculations reproduce well the present‐day mantle structure including the African and Pacific superplumes and generally support the second proposal with a dynamic cause for the superplume structure. Our results suggest that while the mantle in the African hemisphere before the assembly of Pangea is predominated by the cold downwelling structure resulting from plate convergence between Gondwana and Laurussia, it is unlikely that the bulk of the African superplume structure can be formed before ∼230 Ma (i.e., ∼100 Myr after the assembly of Pangea). Particularly, the last 120 Myr plate motion plays an important role in generating the African superplume. Our models have implications for understanding the global‐scale magmatism, tectonics, mantle dynamics, and thermal evolution history for the Earth since the Early Paleozoic.
Journal Article
Porous spinel-type (Al0.2CoCrFeMnNi)0.58O4-δ high-entropy oxide as a novel high-performance anode material for lithium-ion batteries
Owing to their entropy stabilization and multi-principal effect, transition-metal-based high-entropy oxides are attracting extensive attention as an effective family of anode materials for lithium ion batteries (LIBs). Herein, spinel-type (Al0.2CoCrFeMnNi)0.58O4-δ HEO nanocrystalline powder with high concentration of oxygen vacancies is successfully prepared by the method of solution combustion synthesis (SCS), and explored as a novel anode active material for LIBs. As compared to (CoCrFeMnNi)0.6O4-δ, the inactive Al3+-doped (Al0.2CoCrFeMnNi)0.58O4-δ anode provides more than twice the reversible specific capacity of 554 mAh g−1 after 500 cycles at a specific current of 200 mA g−1, accompanied with good rate capability (634 mAh g−1 even at 3 A g−1) and cycling performance. The enhanced electrochemical properties can be attributed to that inactive Al3+-doping resulted into the more space for Li+ intercalation and deintercalation, enhanced structural stability, and the improved electronic conductivity and Li+ diffusivity.
Journal Article
Cr-spinel records metasomatism not petrogenesis of mantle rocks
Mantle melts provide a window on processes related to global plate tectonics. The composition of chromian spinel (Cr-spinel) from mafic-ultramafic rocks has been widely used for tracing the geotectonic environments, the degree of mantle melting and the rate of mid-ocean ridge spreading. The assumption is that Cr-spinel’s core composition (Cr# = Cr/(Cr + Al)) is homogenous, insensitive to post-formation modification and therefore a robust petrogenetic indicator. However, we demonstrate that the composition of Cr-spinel can be modified by fluid/melt-rock interactions in both sub-arc and sub-mid oceanic mantle. Metasomatism can produce Al-Cr heterogeneity in Cr-spinel that lowers the Cr/Al ratio, and therefore modifies the Cr#, making Cr# ineffective as a geotectonic and mantle melting indicator. Our analysis also demonstrates that Cr-spinel is a potential sink for fluid-mobile elements, especially in subduction zone environments. The heterogeneity of Cr# in Cr-spinel can, therefore, be used as an excellent tracer for metasomatic processes.
Chromian-spinel from mafic-ultramafic rocks is used as a reliable geotectonic and mantle melting indicator. Here, the authors argue that this only works partially – it can be used to assess information on mantle metasomatic processes but not petrogenesis.
Journal Article
Visiting Intangible Cultural Heritage Tourism Sites: From Value Cognition to Attitude and Intention
Intangible cultural heritage (ICH) has recently become an important area of tourism development for many countries that are home to such cultural resources. Within this context, the value of an ICH site has often been used to guide tourism development and policy making. In addition, community residents’ attitude and perception of ICH contribute to tourism development. In this study, we used the traditional firing technology of Longquan celadon in Zhejiang Province, China, as a case study to understand the relationships between value recognition and attitude along with the intention to visit the heritage site. We surveyed 368 residents and conducted path analysis to test such relationships. Findings revealed significant positive correlations between residents’ cognition of ICH value, their attitudes and travel intentions. Among them, attitudes played a mediating role in the formation of value cognition to travel intention. These findings offer insights into ICH-related tourism development, particularly regarding tourism product design, marketing and post-development evaluation, as well as the conservation of ICH sites.
Journal Article
Smart tourism: foundations and developments
Smart tourism is a new buzzword applied to describe the increasing reliance of tourism destinations, their industries and their tourists on emerging forms of ICT that allow for massive amounts of data to be transformed into value propositions. However, it remains ill-defined as a concept, which hinders its theoretical development. The paper defines smart tourism, sheds light on current smart tourism trends, and then lays out its technological and business foundations. This is followed by a brief discussion on the prospects and drawbacks of smart tourism. The paper further draws attention to the great need for research to inform smart tourism development and management.
Journal Article
Cytokinins as central regulators during plant growth and stress response
Key messageCytokinins are a class of phytohormone that participate in the regulation of the plant growth, development, and stress response. In this review, the potential regulating mechanism during plant growth and stress response are discussed.Cytokinins are a class of phytohormone that participate in the regulation of plant growth, physiological activities, and yield. Cytokinins also play a key role in response to abiotic stresses, such as drought, salt and high or low temperature. Through the signal transduction pathway, cytokinins interact with various transcription factors via a series of phosphorylation cascades to regulate cytokinin-target gene expression. In this review, we systematically summarize the biosynthesis and metabolism of cytokinins, cytokinin signaling, and associated gene regulation, and highlight the function of cytokinins during plant development and resistance to abiotic stress. We also focus on the importance of crosstalk between cytokinins and other classes of phytohormones, including auxin, ethylene, strigolactone, and gibberellin. Our aim is to provide a comprehensive overview of recent findings on the mechanisms by which cytokinins act as central regulators of plant development and stress reactions, and highlight topics for future research.
Journal Article